1. Field of the Invention
The present invention relates to systems of machines for reshaping cylindrical metal bodies, i.e., cans. In particular, the present invention is directed to a linking apparatus and method for connecting different machines that are used to shape cans.
2. Description of the Related Art
There are a wide variety of cylindrical containers constructed from different materials and in different configurations to accommodate a wide variety of uses. Various types of ductile metal cans are used to provide packaging for a wide variety of foods, beverages and others products, the package being hermetically sealed and possibly under natural or created pressure conditions, or under vacuum.
One popular can, offered in different sizes, is the so-called beer/beverage can having a unitary drawn can body to which an easy-opening end is attached after filling. Other cans, often of the wide-mouth type, are used to package cheese spreads, nuts, and other food products which may be only hermetically sealed, or may be vacuum packed in some instances or packed with an inert gas under pressure in other instances. Additionally, products that use aerosol or other propellants are commonly packaged in metal cans.
In aggregate, the market demand for all of the various types of metal body cans amounts to billions of units.
Originally, metal cans were formed of three separate pieces. A rectangular metallic sheet was rolled into a cylinder, with the seam portion along its length being soldered or welded to a leak-proof state. The top and bottom edges of the cylindrical body were flanged to accept an end wall element at each end thereof. The end walls were sealed to the cylindrical body by means of the conventional double seaming operation.
More recently, three-piece container bodies have been increasingly replaced, especially in the beverage field, with two-piece drawn and ironed cans. In such a system, a circular blank of sheet material is drawn into a cup-like shape. Subsequently, the cup is redrawn to lengthen the sidewall and reduce the diameter thereof. Next, the sidewall is lengthened and thinned by ironing between punch and die members. Finally, the closed bottom is forced against a bottom former, which shapes the bottom portion, adding strength to the container.
At first, these two-piece containers were flanged and given a single end wall in the same manner as the three-piece container. However, since both top and bottom end walls were not necessary, space savings in storage of filled containers and metal usage reduction could be realized by necking the open edge portion of the container body inwardly, prior to placing the end wall thereon, such that the end wall diameter did not exceed the side wall diameter of the container body. Such an inward necking of container bodies is now commonplace.
In a further attempt to reduce metal usage, it was next proposed to reduce further the diameter of the open container edge by means of additional necking stages. Thus, container bodies were necked as many as eight times, then flanged, on a single fixed base machine. This proved successful in further reducing metal usage, without substantially adversely affecting the container.
Traditional installations combined the various processing stages in a single "fixed base" machine. Such fixed base machines were extremely large, heavy and cumbersome to ship and install. Moreover, these fixed base machines could not be reconfigured to accommodate alternative or additional processes.
More recently, installations for making and processing cans of metal are known in which the ironing of the can bodies from cups, the trimming of the can rim, the forming of the can bottom, the washing and drying, inside coating and decorating, and finally also the making of the can rim and the flanging are carried out in successive operations on separate machines. Relatively expensive transporting devices interconnect these separate machines. Because the production output of these interconnected separate machines is not always the same, it becomes necessary to incorporate branches in the transporting devices, as well as accumulation devices, for the production flow to split or be rejoined.
A disadvantage of these known combinations of separate machines and transporting devices is that they also require considerable space because of the relatively great number of individual machines and all the transporting devices that are required between the individual machines. Another disadvantage of these known combinations is that the branching-off and rejoining of production flows requires complicated circuits and systems for controlling the installation. Yet another disadvantage of these known installations is that the transporting devices frequently damage the cans passing through the relatively long and frequent direction-changing path.
Over the years, the assignee of the present invention has been responsible for numerous advances in can making technology. These innovations have enabled increases in line speed and improvements in quality and productivity, while significantly reducing materials costs. Previously, the assignee has introduced such innovations as a tandem drive system and a modular necking system.
The assignee's tandem drive system 100 is illustrated in FIGS. 6-8. The tandem drive system 100 commonly drives two otherwise separate machines 102 and 104 with a single motor 110. A pair of drive pulleys 112 are identically driven by the motor 110. A pair of drive belts 114 and 116 transfers torque from the drive pulleys 112 to a pair of driven pulleys 118 and 120, respectively. Torque from the driven pulley 118 is transferred to the first machine 102 via a right-angle drive unit 122, and torque from the driven pulley 120 is transferred to the second machine 104 via a right-angle drive unit 124.
A vacuum star-wheel 130 is used to convey cans from the first machine 102 to the second machine 104. The star-wheel 130 includes a plurality of pockets 132 around its circumferential periphery for engaging and moving a sequential flow of can bodies. Each of the pockets 132 is shaped to correspond to the curvature of the can bodies and includes one or more suction surfaces (not shown) for engaging and retaining a can body in a respective one of the pockets 132. The star-wheel 130 is rotated via an arrangement 140 including a drive pulley 142 turned by the first machine 102, a drive belt 144, and a driven pulley 146 connected to the star-wheel 130.
Referring to FIG. 8, a pair of idler wheels 148 ensure that the drive pulley 142 rotates in the opposite direction of rotation with respect to the driven pulley 146. This is necessary for handing-off the can bodies from the first machine 102 to the star-wheel 130. A tension wheel 150 ensures that the drive belt 144 transfers the torque between the drive pulley 142 and the driven pulley 146.
In operation, the pockets 132 are controllably connected to a vacuum source 106 of the first machine 102 for selectively engaging and releasing a can body. The can bodies are engaged and released based on the angular position of the star-wheel 130 and the relative position of a pocket with respect to the first and second machines 102 and 104.
The assignee's modular necking system is described in U.S. Pat. No. 5,611,231, which is hereby incorporated by reference. The modular necking system dramatically decreases wasted floor space, can damage, labor and training. The reduction of costly space and air consuming trackwork, elevators and other redundant equipment offers a significantly simpler process and significant savings. The modular system minimizes installation and platform costs, and controls can transportation throughout the entire process. This reduced can handling, as compared to that of interconnecting trackwork and conveyors, preserves can quality and reduces spoilage.
Applicants of the present invention have recognized that there is a need to provide a coupling between different combinations of fixed base and modular can making machines